In some instances it is difficult to lower a towable body to the water while the towable body is alongside a "mother" ship (see FIG. 1). The main difficulty is with the effect of the motion of the mother ship on the towable body as the towable body is lowered to the water. The rocking motion of the mother ship is magnified in the motion of the towable body, switching from side to side at the end of booms and long cables. The motion of the towable body can become so extreme as to risk damage to itself and the mother ship, as well as workmen engaged in the operation.
One conventional way of stopping or at least limiting the swinging motion of the towable body is by attaching extra cables to the towable body which extend laterally to the mother ship in a restraining mode. However, this procedure may be somewhat unwieldy for launching a very heavy and cumbersome towable body, for example, a seismic subarray which may be up to 60 feet long, weigh up to 25,000 pounds, and have attached gear such as seismic guns and umbilical cables which are subject to entanglement. Accordingly, considering both the size and unwieldy dimensions of a seismic subarray, it is desirable to have a launch system which avoids the manifest problems of the art.
Applicant is not aware of any prior art references which, in his judgment as one skilled in the art of launching seismic subarrays, would anticipate or render obvious the novel launch method and apparatus of the instant invention.